The present invention concerns a crankshaft assembly effecting variable piston stroke and hence an engine with a variable compression ratio.
U.S. Pat. No. 4,485,768, issued to the present inventor, was based upon an engine having the capability of operating through a range of different strokes and compression ratios. A drive mechanism of the engine included gear sets provided for the purpose of shifting the rotational axis of the engine crankshaft for the purpose of altering the effective throw of a crankpin and piston stroke. While the proposed mechanism constituted a substantial contribution to engine art, the complexity of the engine was objectionable. The background of the variable stroke engine as set forth in the above U.S. patent is incorporated herein by reference to the extent such background is relevant.
U.S. Pat. No. 3,861,239 discloses an engine connecting rod journalled on an eccentric.
Prior engine art includes engines with combustion chambers with auxiliary chambers for the purpose of varying engine compression ratio per U.S. Pat. No. 4,182,288. Further, the prior art includes engines with opposed pistons wherein a slider element is lever mounted and moves about an adjustable fulcrum enabling varying of the piston stroke as shown in British Pat. No. 229,430. For certain reasons engine designs embodying mechanisms for varying compression have not resulted in engines accepted by the public. An apparent shortcoming of known engine designs is that the proposed designs are cumbersome, of doubtful reliability with components subject to unacceptable loads. Further, proposed variable stroke engines result in objectionable engine envelopes as per the engine in U.S. Pat. Nos. 4,270,495, 3,686,972 discloses an eccentric on a crankpin of a crankshaft.